With the ongoing miniaturization of semiconductor elements to achieve even faster chips, higher processing capability, and broader fields of application, the manufacturing thereof becomes more an more challenging. Conventional manufacturing methods such as lithographic methods are approaching the boundaries of what is achievable in view of the desired dimensions. Therefore, other technologies are being explored that enable to further decrease the scale of dimensions at which semiconductor elements may be manufactured.
Promising technologies that may be applied on a large scale in the future for manufacturing semiconductor elements, include selective etching and selective atomic layer deposition methods, as well as the use of directed self-assembly (DSA) for patterning. In particular implementations of this technology, a self-assembled monolayer (SAM) may be applied as a mask. For example, in case of selective etching the SAM may prevent etching to take place, except for those areas wherein the SAM is interrupted by a void or opening in the monolayer. By pattering such openings in the SAM, selective etching may be performed to form device structures in the material underneath the semiconductor element.
Although the above technique works very well in creating ingenious two dimensional and three dimensional semiconductor device structures of very small dimensions (below 20 nanometer), the technology is prone to defects in the self-assembled monolayer or directed self-assembled layer. A self-assembled monolayer is a very fragile monolayer of molecules that may be 1 or 2 nanometers of size. If a single molecule is missing, this will create a defect of at least this size. Directed self-assembled layers are likewise fragile and prone to missing molecules that may interfere with their application, e.g. in a patterning process. For this reason, to prevent critical defects in the semiconductor elements created, inspection of the self-assembled monolayer or directed self-assembled layers (DSA) is to be performed to check for undesired pinholes and for delamination or weaknesses in binding strength of the SAM or DSA to the material underneath.